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Ankle-Brachial Index Test

Exam Overview

This test is done by measuring blood pressure at the ankle and in
the arm while a person is at rest. Some people also do an exercise test. In this case, the blood pressure measurements are repeated at both
sites after a few minutes of walking on a treadmill.

The ankle-brachial index (ABI) result is used to predict the
severity of
peripheral arterial disease (PAD). A slight drop in
your ABI with exercise means that you probably have PAD. This drop may be
important, because PAD can be linked to a higher risk of heart attack or
stroke.

Why It Is Done

This test is done to check for peripheral arterial disease of the
legs. It is also used to see how well a treatment is working (such as medical
treatment, an exercise program, angioplasty, or surgery).

This test might be done to check your risk of heart attack and stroke. The results can help you and your doctor make decisions about how to lower your risk.footnote 1

Results

The ABI result can help diagnose peripheral arterial disease (PAD).
A lower ABI means you might have PAD. A slight drop in the ABI with exercise,
even if you have a normal ABI at rest, means that you probably have PAD.

Normal

A normal resting ankle-brachial index is 1.0 to 1.4. This means
that your blood pressure at your ankle is the same or greater than the pressure
at your arm, and suggests that you do not have significant narrowing or
blockage of blood flow.footnote 2

Abnormal

Abnormal values for the resting ankle-brachial index are 0.9 or lower and 1.40 or higher. If the
ABI is 0.91 to 1.00, it is considered borderline abnormal.footnote 2

Abnormal values might mean you have a higher chance of having narrowed arteries in other parts of your body. This can increase your risk of a heart attack or stroke.

What To Think About

An abnormal ABI test result may require more testing to
determine the location and severity of PAD that might be present.

You may experience leg pain during the treadmill portion of the
test if you have peripheral arterial disease (PAD).

Stone NJ, et al. (2013). 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437738.63853.7a. Accessed November 18, 2013.

Aboyans V, et al. (2012). Measurement and interpretation of the ankle-brachial index: A scientific statement from the American Heart Association. Circulation, 126(24): 2890–2909.

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